U.S. patent application number 17/310846 was filed with the patent office on 2022-04-07 for two-component aqueous epoxy resin paint.
The applicant listed for this patent is GUANGDONG HUARUN PAINTS CO., LTD.. Invention is credited to Weihua KAI, Luyi WANG, Rong XIONG, Wanjun XU.
Application Number | 20220106494 17/310846 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-07 |
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United States Patent
Application |
20220106494 |
Kind Code |
A1 |
WANG; Luyi ; et al. |
April 7, 2022 |
TWO-COMPONENT AQUEOUS EPOXY RESIN PAINT
Abstract
The present application is directed to a two-component aqueous
epoxy resin paint comprising: a) an aqueous epoxy resin emulsion
comprising a low epoxy equivalent epoxy resin having an epoxy
equivalent weight ranging from 400 to 700 g/eq and a high epoxy
equivalent epoxy resin having an epoxy equivalent weight of greater
than 800 g/eq, and b) a curing agent, wherein a weight ratio of the
low epoxy equivalent epoxy resin to the high epoxy equivalent epoxy
resin is in the range of 5:5 to 9:1; and wherein the aqueous epoxy
resin emulsion is a stable emulsion.
Inventors: |
WANG; Luyi; (Shanghai,
CN) ; KAI; Weihua; (Foshan City, Guangdong Province,
CN) ; XIONG; Rong; (Foshan City, Guangdong Province,
CN) ; XU; Wanjun; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GUANGDONG HUARUN PAINTS CO., LTD. |
Foshan City, Guangdong Province |
|
CN |
|
|
Appl. No.: |
17/310846 |
Filed: |
January 7, 2020 |
PCT Filed: |
January 7, 2020 |
PCT NO: |
PCT/CN2020/070706 |
371 Date: |
August 26, 2021 |
International
Class: |
C09D 163/00 20060101
C09D163/00; C08G 59/22 20060101 C08G059/22; C08G 59/24 20060101
C08G059/24; C08G 59/50 20060101 C08G059/50; C08G 59/54 20060101
C08G059/54; C08G 59/40 20060101 C08G059/40; C09D 5/02 20060101
C09D005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2019 |
CN |
201910154749.4 |
Claims
1. A two-component aqueous epoxy resin paint comprising: a) an
aqueous epoxy resin emulsion comprising a low epoxy equivalent
epoxy resin having an epoxy equivalent weight ranging from 400 to
700 g/eq and a high epoxy equivalent epoxy resin having an epoxy
equivalent weight of greater than 800 g/eq, and b) a curing agent,
wherein a weight ratio of the low epoxy equivalent epoxy resin to
the high epoxy equivalent epoxy resin is in the range of 5:5 to
9:1; and wherein the aqueous epoxy resin emulsion is a stable
emulsion.
2. The two-component aqueous epoxy resin paint according to claim
1, wherein the high epoxy equivalent epoxy resin has an epoxy
equivalent weight in the range of from 900 g/eq to 2500 g/eq.
3. The two-component aqueous epoxy resin paint according to claim
1, wherein the high epoxy equivalent epoxy resin forms a
crosslinked epoxy resin having a glass transition temperature of
50.degree. C. or higher after being mixed with the curing
agent.
4. The two-component aqueous epoxy resin paint according to claim
1, wherein any one of the low epoxy equivalent epoxy resin and the
high epoxy equivalent epoxy resin is a diglycidyl ether of
polyhydric phenol of formula (I): ##STR00002## wherein D each
represents divalent C.sub.1-C.sub.10 alkylene, Y each independently
represents hydrogen, halogen or optionally substituted monovalent
C.sub.1 to C.sub.10 hydrocarbon group, m each independently
represents 0, 1, 2, 3 or 4, and n represents an integer from 0 to
4.
5. The two-component aqueous epoxy resin paint according to claim
1, wherein the aqueous epoxy resin emulsion further comprises: a
reactive emulsifier, an optional coalescent agent; and an aqueous
medium, wherein the reactive emulsifier is an adduct formed by the
addition of an epoxy resin and a nonionic surfactant.
6. The two-component aqueous epoxy resin paint according to claim
1, wherein the aqueous epoxy resin emulsion is formed by mixing a
first emulsion comprising the low epoxy equivalent epoxy resin and
a second emulsion comprising the high epoxy equivalent epoxy
resin.
7. The two-component aqueous epoxy resin paint of claim 6, wherein
the first emulsion is a stable emulsion.
8. The two-component aqueous epoxy resin paint according to claim
6, wherein the first emulsion has a solid content of 40 to 60% by
weight.
9. The two-component aqueous epoxy resin paint of claim 6, wherein
the second emulsion is a stable emulsion.
10. The two-component aqueous epoxy resin paint according to claim
6, wherein the second emulsion has a solid content of 40 to 60% by
weight.
11. The two-component aqueous epoxy resin paint according to claim
6, wherein the aqueous epoxy resin emulsion comprises, relative to
the total weight of the aqueous epoxy resin emulsion, 10-70% by
weight of the combination of the first emulsion and the second
emulsion; 0-30% by weight of fillers; 0-60 wt % of an additional
additive comprising a wetting dispersant, an antifoaming agent, a
leveling agent, a rust inhibitor, a coalescent agent, a rheology
modifier, an aqueous solvent, a pigment, or any combination
thereof.
12. The two-component aqueous epoxy resin paint according to claim
1, wherein the curing agent comprises an aliphatic polyamine, a
fatty amine adduct, an amidoamine, an amino polyamide resin, a
cycloaliphatic amine, an aromatic amine, an arylamine, a Mannich
base, a ketimine, and a dicyandiamide or combinations thereof.
13. The two-component aqueous epoxy resin paint according to claim
1, wherein the aqueous epoxy resin emulsion after being mixed with
the curing agent exhibits a pot life of at least 2 hours at
40.degree. C.
14. The two-component aqueous epoxy resin paint according to claim
1, wherein the aqueous epoxy resin emulsion after being mixed with
the curing agent forms a paint film that exhibits an initial
sanding property of 5.sup.- or higher after baking at 60.degree. C.
for 0.5 h.
15. The two-component aqueous epoxy resin paint according claim 1,
which is suitable for use as a primer, a topcoat, an intermediate
coat or a primer topcoat syncretic coating.
Description
CROSS-REFERENCE OF RELEVANT APPLICATION
[0001] This application claims priority of Chinese patent
application No. 201910154749.4 entitled "two-component aqueous
epoxy resin paint" and filed on Mar. 1, 2019, which is incorporated
herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to a two-component aqueous
epoxy resin paint, and more specifically to a two-component aqueous
epoxy resin paint with a balanced pot life and drying speed.
BACKGROUND
[0003] Epoxy resin has a wide range of application in coating
industry. It is well known that an epoxy resin-curing system (also
known as two-component epoxy resin paint) after curing can obtain a
coating having good adhesion to substrates, especially metals, and
having high mechanical strength, good chemical resistance and
corrosion resistance. Therefore, an epoxy resin paint is considered
to be one of the most cost-effective coating compositions in
practice.
[0004] With the increasing awareness of environmental protection,
the development of aqueous epoxy resin paint has attracted more and
more attention. At present, how to ensure that a two-component
aqueous epoxy paint has a rapid drying and a long pot life at the
same time is an industry problem that has been difficult to solve
for a long time, and it has never been properly solved before.
Compared with a solvent-borne epoxy paint, an aqueous epoxy paint
has a shorter pot life, especially at higher application
temperatures. For example, at a construction temperature of
40.degree. C., pot life of the conventional two-component aqueous
epoxy paints is usually only 1 hour, which severely limits use of
the two-component aqueous epoxy paints in regions with higher
temperatures (such as tropical region). It has been proposed to
replace a fast-drying curing agent with a slow-drying curing agent
to increase pot life of products by sacrificing fast-drying
performance, but this solution cannot be applied to the actual
formulation.
[0005] Therefore, there is a need in the coating industry to a
two-component aqueous epoxy resin paint with a balanced pot life
and drying speed.
SUMMARY
[0006] The present application provides a two-component aqueous
epoxy resin paint, comprising: a) an aqueous epoxy resin emulsion
comprising a low epoxy equivalent epoxy resin having an epoxy
equivalent weight ranging from 400 to 700 g/eq and a high epoxy
equivalent epoxy resin having an epoxy equivalent weight of greater
than 800 g/eq, and b) a curing agent, wherein a weight ratio of the
low epoxy equivalent epoxy resin to the high epoxy equivalent epoxy
resin is in the range of 5:5 to 9:1; and wherein the aqueous epoxy
resin emulsion is a stable emulsion.
[0007] In one embodiment of the present invention, the aqueous
epoxy resin emulsion is formed by mixing a first emulsion
comprising the low epoxy equivalent epoxy resin and a second
emulsion comprising the high epoxy equivalent epoxy resin.
Preferably, the first emulsion is a stable emulsion. More
preferably, the first emulsion is a stable emulsion, and the second
emulsion is also a stable emulsion.
[0008] It was surprisingly discovered by the inventors of the
present invention that in the formulation of two-component aqueous
epoxy resin paint, when the aqueous epoxy resin emulsion is stable
and comprises a combination of a low epoxy equivalent epoxy resin
and high epoxy equivalent epoxy with a specific weight ratio, the
resulting two-component aqueous epoxy resin paint not only has a
balanced pot life and drying performance, but also shows an
excellent corrosion resistance.
[0009] Without wishing to be bound by any theory, it is speculated
that the two-component aqueous epoxy resin paint of the present
invention can achieve the above-mentioned effects for the following
reasons. The inventors of the present invention pioneered to
discover that unlike a solvent-borne epoxy resin paint, the pot
life of an aqueous epoxy resin paint is not only affected by
crosslinking reaction between epoxy group of an epoxy resin and a
curing agent, but also affected by demulsification of the aqueous
epoxy resin emulsion which is also an important factor. The aqueous
epoxy resin emulsion does not demulsify during the pot life, making
it possible that the two-component aqueous epoxy resin paint formed
therefrom has an acceptable pot life, for example, a pot life at
40.degree. C. of 2 hours or more. Moreover, according to an
embodiment of the present invention, the aqueous epoxy resin
emulsion contains a combination of a low epoxy equivalent epoxy
resin and a high epoxy equivalent epoxy resin in which the high
epoxy equivalent epoxy resin provides an initial sanding property
for epoxy paint film and the low epoxy equivalent epoxy resin
provides a certain crosslinking degree for epoxy resin paint film,
so that the two-component epoxy resin paint formed therefrom has a
suitable drying performance. Further, according to an embodiment of
the present invention, the aqueous epoxy resin emulsion contains a
combination of a low epoxy equivalent epoxy resin and a high epoxy
equivalent epoxy resin in a specific ratio, and the proportion of
the low epoxy equivalent epoxy resin is higher. Therefore, the
paint film formed from the two-component epoxy resin paint has an
ideal crosslinking density and shows excellent corrosion
resistance.
[0010] Therefore, the present invention provides a two-component
aqueous epoxy resin paint with a balanced long pot life and fast
drying speed, and the coating formed from the paint has an
excellent corrosion resistance.
[0011] The details of one or more embodiments of the present
disclosure are set forth in the description below. Other features,
objects, and advantages of the present disclosure will be apparent
from the description, and from the claims.
DESCRIPTION FOR DRAWINGS
[0012] FIG. 1 shows curves of particle size of different types of
epoxy resin emulsions after mixing with a curing agent with time at
40.degree. C.
DEFINITION
[0013] As used herein, "a", "an", "the", "at least one", and "one
or more" are used interchangeably. Thus, for example, a composition
that comprises "an" additive can be interpreted to mean that the
composition includes "one or more" additives.
[0014] Throughout the present disclosure, where compositions are
described as having, including, or comprising specific components
or fractions, or where processes are described as having,
including, or comprising specific process steps, it is contemplated
that the compositions or processes as disclosed herein may further
comprise other components or fractions or steps, whether or not,
specifically mentioned in this invention, as along as such
components or steps do not affect the basic and novel
characteristics of the present disclosure, but it is also
contemplated that the compositions or processes may consist
essentially of, or consist of, the recited components or steps.
[0015] For the sake of brevity, only certain ranges are explicitly
disclosed herein. However, ranges from any lower limit may be
combined with any upper limit to recite a range not explicitly
recited, as well as, ranges from any lower limit may be combined
with any other lower limit to recite a range not explicitly
recited, in the same way, ranges from any upper limit may be
combined with any other upper limit to recite a range not
explicitly recited. Additionally, within a range includes every
point or individual value between its end points even though not
explicitly recited. Thus, every point or individual value may serve
as its own lower or upper limit combined with any other point or
individual value or any other lower or upper limit, to recite a
range not explicitly recited.
[0016] When used herein, the term "epoxy equivalent weight" refers
to the mass of epoxy resin containing 1 mol of epoxy groups.
Generally, the lower the epoxy equivalent weight, the more epoxy
groups contained in the epoxy resin is, and the higher the
reactivity is. In an embodiments of the present invention, epoxy
equivalent weight of the epoxy resin is usually provided by
suppliers.
[0017] When used for an aqueous epoxy resin emulsion, a first
emulsion containing a low epoxy equivalent epoxy resins, and a
second emulsion containing a high epoxy equivalent epoxy resins,
the term "stable" means that after the emulsion and a curing agent
are mixed in an equivalent ratio of 1:0.8 and the resulting mixture
is stored at 40.degree. C. for 2 hours, particle size of the
emulsion does not exceed twice its initial particle size.
[0018] When used for a two-component aqueous epoxy paint, the term
"pot life" refers to the time it takes for the viscosity of the
system obtained by mixing two components of the epoxy resin paint
to reach twice the initial viscosity of the system at a temperature
of 40.degree. C.
[0019] When used for a two-component aqueous epoxy paint, the term
"initial sanding property" is a parameter used to measure drying
performance of the two-component aqueous epoxy resin paint.
Generally, the higher the initial sanding property, the better
drying performance of the paint film is.
[0020] When used herein, the term "primer" refers to a coating
composition that can be applied to a metal substrate and dried,
crosslinked, or otherwise hardened to form a non-sticky continuous
film having sufficient adhesion to the surface of substrate.
[0021] When used herein, the term "topcoat" refers to a coating
composition that can be applied to a primer and dried, crosslinked,
or otherwise hardened to form a decorative or protective outermost
finish. Further, such topcoat can withstand long-term outdoor
exposure without showing visible and unsatisfactory
deterioration.
[0022] When used herein, the term "intermediate paint" refers to a
coating composition that can be applied between a primer and a
topcoat and dried, crosslinked or otherwise hardened to form one or
more non-tacky continuous films between the primer and the
topcoat.
[0023] When used herein, the term "direct-to-metal coating (DTM)"
refers to a coating composition that can be applied to a metal
substrate and dried, crosslinked, or otherwise hardened to form a
non-sticky continuous film that has sufficient adhesion on the
surface of substrate, and can withstand long-term outdoor exposure
without showing visible and unsatisfactory deterioration.
[0024] The term "comprises", "comprising", "contains" and
variations thereof do not have a limiting meaning where these terms
appear in the description and claims.
[0025] The terms "preferred" and "preferably" refer to embodiments
of the present disclosure that may afford certain benefits, under
certain circumstances. However, other embodiments may also be
preferred, under the same or other circumstances. Furthermore, the
recitation of one or more preferred embodiments does not imply that
other embodiments are not useful, and is not intended to exclude
other embodiments from the scope of the present disclosure.
DETAILED DESCRIPTION
[0026] The present application provides a two-component aqueous
epoxy resin paint, comprising: a) an aqueous epoxy resin emulsion
comprising a low epoxy equivalent epoxy resin having an epoxy
equivalent weight ranging from 400 to 700 g/eq and a high epoxy
equivalent epoxy resin having an epoxy equivalent weight of greater
than 800 g/eq, and b) a curing agent, wherein a weight ratio of the
low epoxy equivalent epoxy resin to the high epoxy equivalent epoxy
resin is in the range of 5:5 to 9:1; and wherein the aqueous epoxy
resin emulsion is a stable emulsion.
Aqueous Epoxy Resin Emulsion
[0027] In the present invention, the aqueous epoxy resin emulsion
refers to a resin composition that constitutes main body of coating
formed from the two-component aqueous epoxy resin paint of the
present invention, and the aqueous epoxy resin emulsion is a stable
emulsion. In the context of the present invention, "stable" means
that after the emulsion and a curing agent are mixed in an
equivalent ratio of 1:0.8 and the resulting mixture is stored at
40.degree. C. for 2 hours, particle size of the emulsion does not
exceed twice its initial particle size.
[0028] Pot life of aqueous epoxy resin paint is one of the
important factors that determine its application value. So far,
there has been no recognition in the paint industry that unlike a
solvent-borne epoxy resin paint, the pot life of an aqueous epoxy
resin paint is not only affected by crosslinking reaction between
epoxy group of an epoxy resin and a curing agent, also affected by
demulsification of the aqueous epoxy resin emulsion which is also
an important factor. The inventors of the present invention
pioneered to discover that using a stable aqueous epoxy resin
emulsion, a two-component water-based epoxy paint with an
acceptable pot life can be successfully formulated, such as, with a
pot life at 40.degree. C. of 2 hours or longer, for example 3 hours
or longer.
[0029] According to some embodiments of the present invention, the
aqueous epoxy resin emulsion comprises a low epoxy equivalent epoxy
resin with an epoxy equivalent weight between 400-700 g/eq and a
high epoxy equivalent epoxy resin with an epoxy equivalent weight
of greater than 800 g/eq, wherein the weight ratio of the low epoxy
equivalent epoxy resin to the high epoxy equivalent epoxy resin is
in the range of 5:5 to 9:1.
[0030] The term "epoxy resin" as used herein refers to a polymer or
oligomer containing two or more epoxy groups in one molecule.
Preferably, the epoxy resin contains at most four epoxy groups in
one molecule. More preferably, the epoxy resin contains two or
three epoxy groups in one molecule. According to some embodiments
of the present invention, the epoxy resin may have an epoxy
equivalent varying over a wide range, wherein the epoxy equivalent
is the mass of an epoxy resin containing 1 mole of epoxy group. For
example, the epoxy resin may comprise a low epoxy equivalent epoxy
resin and a high epoxy equivalent epoxy resin. As used herein, the
epoxy resin having an epoxy equivalent between 400 and 700 g/eq,
preferably between 450 and 550 g/eq is known as a low epoxy
equivalent epoxy resin. The epoxy resin having a higher epoxy
equivalent, such as having an epoxy equivalent greater than 800
g/eq, is known as a high epoxy equivalent epoxy resin. Preferably,
the high epoxy equivalent epoxy resin may have an epoxy equivalent
in the range of 900 g/eq to 2500 g/eq. In some embodiments, the
high epoxy equivalent epoxy resin may have an epoxy equivalent in
the range of 850 g/eq to 1200 g/eq. In some embodiments, the high
epoxy equivalent epoxy resin may have an epoxy equivalent in the
range of 1400 g/eq to 2500 g/eq, for example, in the range of 1600
to 1800 g/eq, or in the range of 1700 to 2200 g/eq.
[0031] According to some embodiments of the present invention, the
high epoxy equivalent epoxy resin contained in the aqueous epoxy
resin emulsion can obtain a significantly increased glass
transition temperature after being mixed with a curing agent, so
that the paint film has a better initial sanding property (i.e.
initial hardness), thereby rendering the two-component epoxy paint
formed therefrom to have a suitable drying performance. Preferably,
according to some embodiments of the present invention, the high
epoxy equivalent epoxy resin will form a crosslinked epoxy resin
with a glass transition temperature of 50.degree. C. or higher,
preferably a crosslinked epoxy resin with a glass transition
temperature of 55.degree. C. or higher, more preferably a
crosslinked epoxy resin with a glass transition temperature of
60.degree. C. or higher and even more preferably a crosslinked
epoxy resin with a glass transition temperature of 70.degree. C. or
higher after being mixed with the curing agent.
[0032] According to some embodiments of the present invention, the
low epoxy equivalent epoxy resin contained in the aqueous epoxy
resin emulsion can provide a sufficient degree of crosslinking, so
that the paint film of the two-component epoxy resin paint formed
therefrom has an ideal crosslink density. Therefore, in the
formulation of two-component epoxy resin paint, low epoxy
equivalent epoxy resin is also an important component.
[0033] Suitable epoxy resin comprises, for example diglycidyl ether
of polyhydric phenol, such as diglycidyl ether of resorcinol,
diglycidyl ether of catechol, diglycidyl ether of hydroquinone,
diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F,
diglycidyl ether of bisphenol S, diglycidyl ether of tetramethyl
bisphenol; diglycidyl ether of polyalcohol, such as diglycidyl
ether of aliphatic diglycol and diglycidyl ether of polyether
glycol, for example diglycidyl ether of C.sub.2-24 alkylene glycol,
diglycidyl ether of poly(ethylene oxide) glycol or diglycidyl ether
of poly(propylene oxide) glycol; or polyglycidyl ether of novolack
resin, such as polyglycidyl ether of phenol-formaldehyde resin,
polyglycidyl ether of alkyl substituted phenol-formaldehyde resin,
polyglycidyl ether of phenol-hydroxyl benzaldehyde resin, or
polyglycidyl ether of cresol-hydroxyl benzaldehyde resin; or the
combination thereof.
[0034] According to some embodiments of the present disclosure, any
one of the low epoxy equivalent epoxy resin and the high epoxy
equivalent epoxy resin is a diglycidyl ether of polyhydric phenol,
especially preferably having the structure of formula (I):
##STR00001##
wherein D each represents --S--, --S--S--, --SO--, --SO.sub.2--,
--CO.sub.2--, --CO--, --O-- or C.sub.1 to C.sub.10 alkylene,
preferably C.sub.1 to C.sub.5 alkylene, more preferably C.sub.1 to
C.sub.3 alkylene, such as --CH.sub.2-- or --C(CH.sub.3).sub.2--, Y
each independently represents halogen, such as F, Cl, Br, or I, or
optionally substituted monovalent C.sub.1 to C.sub.10 hydrocarbon
group, such as optionally substituted methyl, ethyl, vinyl, propyl,
allyl or butyl; m each independently represents 0, 1, 2, 3 or 4,
and n represents an integer from 0 to 4, such as 0, 1, 2, 3 or
4.
[0035] More preferably, any one of the low epoxy equivalent epoxy
resin and the high epoxy equivalent epoxy resin is bisphenol A
epoxy resin, bisphenol S epoxy resin or bisphenol F epoxy resin
having the structure of formula (I) in which D represents
--C(CH.sub.3).sub.2--, --SO.sub.2-- or --CH.sub.2-- respectively, m
represents 0, and n represents an integer from 0 to 4.
[0036] Most preferably, any one of the low epoxy equivalent epoxy
resin and the high epoxy equivalent epoxy resin is bisphenol A
epoxy resin having the structure of formula (I) in which D
represents --C(CH.sub.3).sub.2--, m represents 0, and n represents
an integer from 0 to 4.
[0037] The epoxy resin as disclosed herein may be prepared by the
epichlorohydrin technology which is well-known by those skilled in
the art, for example. Alternatively, as an example of epoxy resin,
any suitable commercial product may be used, for example E55, E51,
E44, or E20 available from Kaiping Resin Company, Shanghai,
China.
[0038] According to the present application, the above mentioned
epoxy resin is used for providing a resin component for the aqueous
epoxy resin emulsion. In one aspect, the resin component functions
as a binder which provides adhesion to a substrate, and holds
together other components, such as fillers, of the epoxy resin
paint to impart basic cohesive strength to the paint film formed
from the epoxy resin paint of the present disclosure. In the other
aspect, the resin component has good reactivity with a curing
agent, thereby providing a coating having high mechanical
strength.
[0039] In the aqueous epoxy resin emulsion according to the present
invention, the weight ratio of the low epoxy equivalent epoxy resin
to the high epoxy equivalent epoxy resin can be varied within a
wide range. Preferably, compared to the weight of the high epoxy
equivalent epoxy resin contained in the aqueous epoxy resin
emulsion, the low epoxy equivalent epoxy resin is present in a
higher weight percentage. For example, the weight ratio of the low
epoxy equivalent epoxy resin and the high epoxy equivalent epoxy
resin is in the range of 5:5 to 9:1, preferably in the range of 5:5
to 8:2. The inventors of the present invention surprisingly found
that the paint film of the two-component epoxy resin paint
formulated by the above ratio has an ideal crosslinking density and
exhibits an excellent corrosion resistance.
[0040] According to some embodiments of the present invention, the
aqueous epoxy resin emulsion further comprises a reactive
emulsifier, an optional film-forming aid, and an aqueous medium,
wherein the reactive emulsifier is an adduct formed by the addition
of an epoxy resin, such as an epoxy resin having an epoxy
equivalent of less than 600 g/eq and a nonionic surfactant. The
inventors of the present invention surprisingly found that the
aqueous epoxy resin emulsion with the above composition is stable
during the pot life and its particle size at 40.degree. C. can be
kept unchanged for a relatively long period of time, such as 2
hours, 3 hours, 4 hours or longer after being mixed with a curing
agent,
[0041] According to an embodiment of the present invention, the
reactive emulsifier is an adduct formed by the addition of an epoxy
resin, such as an epoxy resin having an epoxy equivalent of less
than 600 g/eq, and a nonionic surfactant. As an exemplary
illustration, the reactive emulsifier can be prepared by
appropriate polyaddition reactions known to those of ordinary skill
in the art. For example, in the presence of a catalyst, the
polymerization reaction of polyethylene glycol and epoxy resin such
as E-20 occurs in water to form a reactive emulsifier. The catalyst
is preferably a Lewis acid, more preferably an anionic Lewis acid,
and most preferably comprises tin tetrachloride, boron trifluoride,
methyl persulfate or triphenylphosphine. The catalyst is preferably
added in the form of a solution, and the solvent for the catalyst
solution is preferably an ether solvent, more preferably ethylene
glycol monoethyl ether. The raw materials, ratio, reaction
conditions, etc. of the above-mentioned synthesis reaction can be
determined by those skilled in the art based on their experience.
Alternatively, the above-mentioned reactive emulsifier may be any
suitable commercially available product as an example, for example,
the EP series aqueous epoxy resin from Allnex, USA.
[0042] According to an embodiment of the present invention, the
film-forming aid is a reagent used to assist the film formation of
epoxy resin, including but not limited to alcohol ethers, such as
propylene glycol monomethyl ether, propylene glycol monobutyl
ether, ethylene glycol monopropyl ether, propylene glycol
monophenyl ether. If necessary, other film-forming aids can also be
used. As examples of other film-forming aids, any appropriate
commercially available products, such as Texanol, Lusolvan FBH,
Coasol, DBE-IB, DPnB, Dowanol PPh, Dowanol PM, alcohol ester 12,
and the like, can be used. If necessary, the above-mentioned
film-forming aids can be present in the aqueous epoxy resin
emulsion, or can be added to the aqueous epoxy resin paint
according to the present invention to promote the formation of
paint film.
[0043] According to an embodiment of the present invention, any
suitable aqueous medium may be used to prepare the aqueous epoxy
resin emulsion of the present invention. Suitable aqueous media
include water-soluble organic solvents, water and mixtures
thereof.
[0044] In a currently preferred embodiment, the aqueous epoxy resin
emulsion is formed by mixing a first emulsion containing the low
epoxy equivalent epoxy resin and a second emulsion containing the
high epoxy equivalent epoxy resin. Preferably, the first emulsion
is a stable emulsion. More preferably, the first emulsion is a
stable emulsion, and the second emulsion is also a stable
emulsion.
[0045] As an example of the first emulsion, any suitable
commercially available product can be used, such as Allnex 387 from
Allnex Corporation. Preferably, the first emulsion has a solid
content of 40-60 wt %.
[0046] As an example of the second emulsion, any suitable
commercially available product can be used, such as 3907 from
Huntsman, 900 and 1600 from Nanya. Preferably, the second emulsion
has a solid content of 40-60 wt %.
[0047] Preferably, the aqueous epoxy resin emulsion contains about
10% to about 70% by weight, preferably about 10% to 60% by weight,
more preferably about 25% to about 55% by weight, still more
preferably about 30% to about 50% by weight of the combination of
the first emulsion and the second emulsion, relative to the total
weight of the aqueous epoxy resin emulsion. Specifically, the
aqueous epoxy resin emulsion, relative to the total weight of the
aqueous epoxy resin emulsion, contains about 30% by weight, about
35% by weight, about 40% by weight, about 45% by weight, about 48%
by weight, or about 50% by weight of the combination of the first
emulsion and the second emulsion.
[0048] A suitable aqueous epoxy resin emulsion may further contain
fillers. The term "filler" as used herein refers to any volume
extender suitable for the aqueous epoxy resin emulsions, which may
be inorganic, for example, in the form of particles. There is no
particular limitation on the shape of particles, and they can have
any appropriate shape. The average particle size of the filler can
vary within a wide range, for example, within a range of about 10
nanometers to about 50 microns. Some fillers, in addition to
functioning as volume extenders, also impart one or more desired
properties to the composition and/or the coating formed from the
composition. For example, some fillers can improve chemical and/or
physical properties, especially mechanical properties of the
coating obtained from the composition. In this case, this filler is
also called "reinforcing filler".
[0049] In an embodiment of the present invention, the fillers
contain, for example, silicate, sulfate, carbonate, and silica.
Suitable exemplary fillers include, for example, kaolin,
wollastonite, calcium carbonate, diatomaceous earth, talc, barium
sulfate, magnesium aluminum silicate, silica, and any combination
thereof.
[0050] According to certain embodiments of the present invention,
the total amount of fillers can vary within a wide range, for
example, the total amount thereof is in the range of about 0% to
about 40% by weight relative to the total weight of the aqueous
epoxy resin emulsion, It is preferably in the range of about 10% by
weight to about 30% by weight, more preferably in the range of
about 10% by weight to 25% by weight.
[0051] According to an embodiment of the present invention, the
aqueous epoxy resin emulsion may further include commonly used
additional additives. Suitable additional additives may include
wetting and dispersing agents, defoamers, leveling agents, rust
inhibitors, film forming aids, rheology modifiers, pigments,
aqueous solvents, or any combination thereof.
[0052] Suitable wetting and dispersing agents may include ionic
wetting and dispersing agents, non-ionic wetting and dispersing
agents, or multifunctional wetting and dispersing agents. As
examples of commercially available wetting and dispersing agents,
Dispers 715 W, Dispers 740W, Dispers 760W, and Disperbyk 194
available from Tego, Germany can be used.
[0053] Suitable defoamers include organosiloxane defoamers,
polyether defoamers, polyether modified silicone defoamers, or any
combination thereof. As examples of commercially available
defoamers, BYK 024, BYK-1660, BYK037, available from BYK, Germany,
and TEGO foamex 810, available from EVONIK, can be used.
[0054] Suitable rheology modifiers (i.e. thickeners) include
polyurethane thickeners, cellulose ether thickeners, or any
combination thereof. As an example of a polyurethane thickener,
RM-8W thickener available from Rohm & Hass, USA can be used. As
an example of a cellulose ether thickener, Bermocoll EBS 451 FQ
available from Akzo Noble, the Netherlands can be used.
[0055] Suitable leveling agents include polysiloxane leveling
agents, polyacrylic leveling agents or any combination thereof. As
an example of a commercially available leveling agent, 1660 and
BYK420 purchased from BYK, Germany can be used.
[0056] As used herein, "rust inhibitor" is an agent that can
prevent corrosion of metal substrates. As an example of a rust
inhibitor, any suitable commercially available product may be used,
such as a flash rust inhibitor Additive F2M commercially available
from Hightac; sodium nitrite or a combination thereof.
[0057] Depending on desired coating color, the aqueous epoxy resin
emulsion may include pigments. Suitable pigments may include one or
more of iron oxide, carbon black, lead oxide, lead carbonate, zinc
oxide, titanium oxide, deep ocean blue, chrome green, or chromium
oxide, or a combination thereof. In a preferred embodiment of the
present invention, titanium oxide is used as a pigment.
[0058] If necessary, the film-forming aids described in the aqueous
epoxy resin emulsion can be used to promote the formation of paint
film, and the type of the film-forming aids is not particularly
limited.
[0059] The content of each optional ingredient is sufficient to
achieve its intended purpose, but preferably, such content does not
adversely affect the coating composition or the cured coating
obtained therefrom. According to certain embodiments of the present
invention, the total amount of the additional additives is in the
range of about 0% to about 60% by weight, preferably in the range
of about 0.1% to about 55% by weight, relative to the total weight
of the aqueous epoxy resin emulsion.
[0060] The preparation of the aqueous epoxy resin emulsion of the
present invention may be achieved by any suitable mixing method
known to those of ordinary skill in the art. For example, an
aqueous epoxy resin emulsion can be made by adding the combination
of the first emulsion and the second emulsion, fillers, and
additional additives (if any) to a container, and then stirring the
resulting mixture uniformly.
Curing Agent
[0061] According to some embodiments of the present invention, the
curing agent used to cure the aqueous epoxy resin emulsion
comprises one or more curing agents selected from an aliphatic
polyamine, a fatty amine adduct, an amidoamine, an amino polyamide
resin, a cycloaliphatic amine, an aromatic amine, an arylamine, a
Mannich base, a ketimine, and a dicyandiamide or combinations
thereof.
[0062] According to some embodiments of the present invention, the
curing agent is well-known in the art, for example it is disclosed
in "Paint Technology" edited by Liu Dengliang, fourth edition,
2010, No. 275-280, the disclosure of which is incorporated herein
by reference.
[0063] According to some embodiments of the present invention, the
weight ratio of the curing agent to the aqueous epoxy resin
emulsion may be varied in the range of 8:100 to 20:100. Generally,
when the weight ratio of the curing agent to the aqueous epoxy
resin emulsion is less than 8:100, the curing performance of the
resulting coating is poor. Generally, when the weight ratio of the
curing agent to the aqueous epoxy resin emulsion is greater than
20:100, the operating performance of the resulting epoxy resin
paint and/or the mechanical properties of the resulting coating may
decrease. According to actual needs, an additional inert diluent
that will not affect reactivity of the curing agent and the aqueous
epoxy resin emulsion can be added during the preparation of the
curing agent and/or the aqueous epoxy resin emulsion, so as to
reduce the components' viscosity. Therefore, the weight ratio of
the curing agent to the aqueous epoxy resin emulsion is not limited
to the above range, and can be adjusted according to actual
needs.
[0064] According to some embodiments of the present invention, the
two-component aqueous epoxy resin paint can be prepared as follows.
Before application, the aqueous epoxy resin emulsion and the curing
agent are simply mixed in a mixing device in a predetermined weight
ratio. The mixed epoxy paint can be applied using various methods
familiar to those skilled in the art, including spraying (for
example, air-assisted, airless or electrostatic spraying),
brushing, roller coating, overflow coating, and dipping. In one
embodiment of the present invention, the mixed epoxy resin paint is
applied by spraying. Epoxy resin paint can be applied as to various
wet film thicknesses. In an embodiment of the present invention,
the epoxy resin paint is applied in such a wet film thickness that
it may preferably provide a dry film thickness of about 13 to about
260 .mu.m (about 0.5 to about 10 mils), and more preferably about
25 to about 75 .mu.m (about 1 to about 10 mils). 3 mils). The
applied coating can be cured by air-drying or by using various
drying devices (for example, an oven) familiar to those skilled in
the art to accelerate the curing. The preferred heating temperature
for curing epoxy resin paint is from about 60.degree. C. to about
100.degree. C., and more preferably from about 60.degree. C. to
about 80.degree. C., and the preferred heating time is from at
least three minutes to less than 60 minutes, to less than 45
minutes, or to less than 40 minutes. The heating time will tend to
decrease with increasing temperature or increasing airflow.
[0065] The present disclosure is more particularly described in the
following examples that are intended as illustrations only, since
numerous modifications and variations within the scope of the
present disclosure will be apparent to those skilled in the art.
Unless otherwise noted, all parts, percentages, and ratios reported
in the following examples are on a weight basis, and all reagents
used in the examples are commercially available and used directly
without further treatment.
Test Methods
Pot Life
[0066] The two components of the aqueous epoxy resin paint of the
present invention were mixed together, which was set standing at
40.+-.1.degree. C., and then the resulting mixture was measured
with a 4 # cup for its viscosity in seconds (s).
Glass Transition Temperature
[0067] The emulsion was centrifuged at a speed of 12000 r/s for 10
minutes to demulsify and was separated. The lower solid was taken
out, dried with N.sub.2, and then subjected to a DSC test (at
10.degree. C./min from -20.degree. C. to 150.degree. C.) in which
the inflection point of the DSC curve is determined as to be
Tg.
Initial Sanding Property
[0068] The two components of the aqueous epoxy resin paint of the
present invention were mixed to form a paint film, and the paint
film was dried and taken out of an oven. The resulting paint film
was immediately polished with 600 grit sandpaper to determine its
initial sanding property. The sanding property was rated to a total
of five grades of 1-5, in which grade 5 was the best, with no paint
film being adhered on sandpaper; grade 4 was second best, with a
small lump being adhered on sandpaper; grade 3 is third best, with
a small amount of medium-sized lump being adhered on sandpaper;
grade 2 is a worse level than grade 3 with a large amount of
medium-sized lump being adhered on sandpaper; and grade 1 was the
worst with a large amount of large lump being adhered on
sandpaper.
[0069] Adhesion was measured according to the test standard of ASTM
D3359.
[0070] Impact resistance was measured according to the Chinese
national standard of GB 1732.
Examples
[0071] The raw materials used in each example were listed in Table
1 below.
TABLE-US-00001 TABLE 1 Items Materials Description 1 Allnex 387
(EEW480-550) Low epoxy equivalent epoxy resin emulsion 2 Hexion
6520 (EEW500-600) Low epoxy equivalent epoxy resin emulsion 3
Huntsman 3907(EEW 1760-2200) High epoxy equivalent epoxy resin
emulsion 4 NanYa 900(EEW 850-1000) High epoxy equivalent epoxy
resin emulsion 5 NanYa1600(EEW1600-1800) High epoxy equivalent
epoxy resin emulsion 6 Disperbyk 194 Wetting and dispersing agent 7
BYK 037 Defoamer 8 BYK420 Leveling agent 9 Additive F2M Rust
inhibitor 10 Deionized water Aqueous medium 12 TiO.sub.2 pigment 13
Rheology modifier Rheology modifier 14 Dowanol PM Film forming aids
15 Sodium nitrite Rust inhibitor
Determination of a First Emulsion
[0072] At room temperature, the commercially available epoxy
emulsions Allnex 387 and Hexion 6520 were mixed with the curing
agent, and then the obtained mixture was detected by a dynamic
light scattering for its particle size change with time at
40.degree. C. The test results were shown in FIG. 1.
[0073] As can be shown from the results, the particle size of
Allnex 387 remained stable, while the particle size of Hexion 6520
rapidly increased in less than 1 hour so that the emulsion broke.
Therefore, Allnex 387 was a stable emulsion, which would be used as
the first emulsion to formulate a two-component aqueous epoxy resin
paint.
Determination of a Second Emulsion
[0074] At room temperature, the commercially available epoxy
emulsions Allnex 387, Huntsman 3907, NanYa 900 and Nanya 1600 were
mixed with the curing agent respectively, and the resulting mixture
was determined according to the test method for their glass
transition temperature. The results were shown in Table 2
below.
TABLE-US-00002 TABLE 2 Allnex 387 Huntsman 3907 NanYa900 NanYa 1600
EEW/g/eq 480-550 1760-2200 850-1000 1600-1800 Tg/.degree. C. 6.7
32.2 7.5 14.3 Tg/.degree. C. after mixing with curing agent 14.5
74.5 60.9 59.1
[0075] As shown from the above results, the epoxy resin emulsions
with a high epoxy equivalents (such as Huntsman 3907, NanYa 900 and
Nanya 1600) had significantly increased Tg after being mixed with a
curing agent. These high epoxy equivalent epoxy resin would form a
crosslinked epoxy resin with a Tg of greater than 50.degree. C.
after being mixed with a curing agent, and a higher Tg would
provide a better initial hardness. Therefore, Huntsman 3907,
NanYa900 and NanYa1600 were considered as the second emulsion that
was suitable for the formulation of the two-component aqueous epoxy
paint.
Two-Component Coating Composition
[0076] As shown in Table 3, Allnex 387 and NY1600 were mixed in a
ratio of 8:2, and then the resulting emulsion was mixed with the
components shown in Table 3 to form an aqueous epoxy resin emulsion
as component A. Then, the obtained component a and the component B
as a curing agent were mixed to form a two-component aqueous epoxy
resin paint according to Example 1 of the present invention. The
two-component aqueous epoxy resin paint of Example 2 was prepared
according to the same method with the exception that Allnex387 and
NY1600 were mixed in a ratio of 7:3.
[0077] For comparison, the epoxy resin emulsion Hexion 6520 was
also mixed with the components shown in Table 3 below to form an
aqueous epoxy resin emulsion as component A. Then, the obtained
component A and the component B as a curing agent were mixed to
form a two-component waterborne epoxy resin paint of the
comparative example 1 for comparison.
[0078] Then, the pot life, adhesion, sanding property and impact
resistance of the two-component aqueous epoxy resin paints of
Example 1, Example 2 and Comparative Example 1 were tested, and the
results were shown in Table 3.
TABLE-US-00003 TABLE 3 Comparative Example Example 2 Example 1
Component Allnex387 38.7 parts by weight 33.9 PBW -- A (PBW)
Nanya1600 9.7 PBW 14.5 PBW -- Hexion6520 -- -- 48.4 PBW Disperbyk
194 3.8 PBW 3.8 PBW 3.8 PBW BYK 037 1.9 PBW 1.9 PBW 1.9 PBW BYK420
6.5 PBW 6.5 PBW 6.5 PBW Additive F2M 11.3 PBW 11.3 PBW 11.3 PBW
Deionized water 11.3 PBW 11.3 PBW 11.3 PBW TiO.sub.2 15.7 PBW 15.7
PBW 15.7 PBW Rheology modifier 0.4 PBW 0.4 PBW 0.4 PBW Dowanol PM
0.5 PBW 0.5 PBW 0.5 PBW Sodium nitrite 0.2 PBW 0.2 PBW 0.2 PBW
Component Curing agent Huntsman3987 13.8 PBW 13.1 PBW 15 PBW B
Properties Pot life 0 h 23.8 s 25.5 s 28.1 s (40.degree. C. ,
4#viscisoity) 1 h -- -- 98.2 s 2 h 24.6 s 26.8 s -- Adhesion 5 5 5
Initial sanding property 5- 5- 4 Impact resistance (cm) 45 45
40
[0079] As shown from the above results, the pot life of the
two-component coating formed by mixing different epoxy emulsions
with different epoxy equivalents was up to 2 h at 40.degree. C.,
and the viscosity did not change much with time; while the
viscosity of the comparative example 1 increased 3 times within
only 1 hour. In addition, the adhesion, sanding property and impact
resistance of the two-component coating formed by mixing different
epoxy emulsions are comparable to those of the comparative example
1. Thus, the water-based epoxy resin paint according to the
embodiment of the present invention was determined to have a
balanced pot life and drying speed.
[0080] While the present disclosure has been described with respect
to a number of embodiments and examples, those skilled in the art,
having benefit of this invention, will appreciate that other
embodiments can be devised which do not depart from the scope and
spirit of the present disclosure as disclosed herein.
* * * * *